$-8cd + 4ce + 7c + 7 = -7d - 6$ Solve for $c$.
Answer: Combine constant terms on the right. $-8cd + 4ce + 7c + {7} = -7d - {6}$ $-8cd + 4ce + 7c = -7d - {13}$ Notice that all the terms on the left-hand side of the equation have $c$ in them. $-8{c}d + 4{c}e + 7{c} = -7d - 13$ Factor out the $c$ ${c} \cdot \left( -8d + 4e + 7 \right) = -7d - 13$ Isolate the $c$ $c \cdot \left( -{8d + 4e + 7} \right) = -7d - 13$ $c = \dfrac{ -7d - 13 }{ -{8d + 4e + 7} }$ We can simplify this by multiplying the top and bottom by $-1$. $c= \dfrac{7d + 13}{8d - 4e - 7}$